A heat dissipating material has been widely used because a semiconductor module generates a lot of heat. On the other hand, the further development has been expected in a power semiconductor used in an electric car, an inverter and a converter of power transmission system, and silicon has been used in a semiconductor element of the power semiconductor. In addition, SiC (silicon carbide) and GaN (gallium nitride) also have been gradually used in the viewpoint of the possibility of greatly decreased power loss, high voltage endurance, and operable property at high temperature, and a heat dissipating material corresponding to these has been required.
Particularly, a thermal interface material (TIM) has been important element in thermal management of the whole semiconductor module. In grease such as silicon which often have been used as this TIM, it is known that a low molecular weight component contained in TIM is separated by use for long time, and the separation of the low molecular weight components has no effect on thermal conductivity. Therefore, a material which is softened at the high temperature without containing a low molecular weight component and serves as TIM is desirable. However, there is a problem that paraffin often has been used as a main raw material, so that it is difficult to exhibit sufficient heat resistance (Patent Document 1).